Recompression chamber

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A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness.

Often the terms recompression chamber, decompression chamber, hyperbaric chamber, and hyperbaric oxygen therapy chamber are used interchangeably. The names reflect the different purposes that the chambers are designed for, rather than their capability. Each is capable, within limits, of operating in the others' role:

A decompression chamber is used in surface supplied diving to allow the divers to complete their decompression stops at the end of a dive on the surface rather than underwater.
A hyperbaric oxygen therapy chamber is used in a hospital or sporting context to treat patients whose condition might benefit from hyperbaric oxygen treatment, including divers. Hyperbaric chambers capable of admitting more than one patient (multiplace) and an inside attendant have advantages for the treatment of decompression sickness and are preferred by the U.S. Coast Guard. Divers with serious complications or injuries may be attended to in this manner during recompression. In addition, multiplace chambers are generally capable of greater depth of recompression, should the need arise. For less seriously ill divers, the more common monoplace chamber is often used, especially if it is the only one available. A modified treatment regimen is then used.
Treatment is ordered by the treating physician (medical diving officer), and is usually in accordance with the U.S. Navy Diving Manual (U.S Navy Diving Tables). Other treatment tables have been developed, including the Catalina Tables, and others, including proprietary tables.
- Test of pressure. If the diagnosis of decompression illness is considered questionable, the diving officer may order a test of pressure. This typically consists of a recompression to 60 feet seawater or up to 20 minutes. If the diver notes significant improvement in symptoms, or the operator can detect changes in the physical examination, a recompression algorithm is followed.
Representative diving tables:
- U.S. Navy Table 6. This diving table consists of compression to the depth of 60 feet seawater with the patient on oxygen. The diver is later decompressed to 30 feet on oxygen, then slowly brought to surface pressure. This table typically takes over three hours and may be extended further. It is the most common treatment for type 2 decompression illness.
- U.S. Navy Table 5. This diving table is similar to Table 6 above, but is shorter in duration. It may be used in divers with less severe complaints (type 1 decompression illness).
- U.S. Navy Table 9. This diving table consists of compression to 45 feet seawater with the patient on oxygen, with later decompression to surface pressure. This table is often used by monoplace hyperbaric chambers, or as a follow-up treatment in multiplace chambers.